Analog level meter and method of measuring analog signal level

ABSTRACT

An analog level meter and a method of measuring an analog signal level may be provided. The analog level meter may include a comparator, a duty counter, an analog level detector and/or a digital to analog converter (DAC). The comparator may compare a voltage level of the analog signal with a reference voltage and generate an up-down signal. The duty counter may count a duty value of the up-down signal. The analog level detector may output a duty error value obtained by subtracting a target duty value from the duty value of the up-down signal. The analog level meter may output the reference voltage as a measured value of the analog signal when the duty error value is a desired or predetermined value.

PRIORITY STATEMENT

This application claims the benefit of priority to Korean PatentApplication No. 10-2006-0004442, filed on Jan. 16, 2006, in the KoreanIntellectual Property Office, the entire contents of which isincorporated herein in its entirety by reference.

BACKGROUND

1. Field

Example embodiments relate to an analog level meter and a method ofmeasuring analog signal level, and for example, to an analog level meterusing duty ratio capable of detecting an analog peak/bottom levelwithout an analog to digital converter and a method of measuring analogsignal level using duty ratio capable of the same.

2. Description of Related Art

An analog level meter may include an analog to digital converter (ADC)to convert an analog signal into a digital signal. However, when afrequency of the analog signal is higher than a sampling frequency ofthe ADC, sampling may not be performed properly. Accordingly, it may benecessary to adjust a level of an input analog signal to improve theoperation of the ADC.

FIG. 1 is an example diagram showing a conventional analog level meterwith an analog to digital converter ADC.

Referring to FIG. 1, the conventional analog level meter 10 may includean offset control unit 11, a gain control unit 12, a peak/bottomdetector 13 and/or an analog to digital converter ADC 14.

The offset control unit 11 and/or the gain control unit 12 may controlan offset and/or a gain of the analog signal to adjust the level of theanalog signal to a level at which the ADC operates properly. Thepeak/bottom detector 13 may detect a peak value and/or a bottom value ofthe analog signal of which the level may be adjusted.

FIGS. 2A and 2B are example circuit diagrams showing a conventionalpeak/bottom detector.

Referring to FIGS. 2A and 2B, the peak/bottom detector 13 may include anoperational amplifier (op amp). The non-inverting terminal of the op ampmay receive the analog signal, and the inverting terminal of the op ampmay receive the output of the op amp by feedback. The peak/bottomdetector 13 may detect the peak value or the bottom value by limiting asource current or a sink current of the op amp.

Referring to FIG. 1, the ADC 14 may perform analog to digital conversionwith respect to the detected peak value and/or bottom value.

However, the conventional analog level meter may have to include theoffset control unit and/or the gain control unit to adjust the level ofthe analog signal to the level at which the ADC operates properly.Accordingly, the layout area of the analog level meter may increase. Theconventional analog level meter may further include capacitors, which inturn, may increase the number of elements and/or change thecharacteristics of the capacitors according to processes.

SUMMARY

Example embodiments provide an analog level meter using duty ratiocapable of detecting a peak/bottom level of an analog signal without ananalog to digital converter.

Example embodiments provide a method of measuring an analog signal levelusing duty ratio capable of detecting a peak/bottom level of an analogsignal without an analog to digital converter.

According to an example embodiment an analog level meter may include acomparator, a duty counter, an analog level detector and/or a digital toanalog converter (DAC). The analog meter may use duty ratio.

According to an example embodiment, the comparator may compare a voltagelevel of an analog signal with a reference voltage and generate anup-down signal. The duty counter may count a duty value of the up-downsignal. The analog level detector may output a duty error value obtainedby subtracting a target duty value from the duty value of the up-downsignal. The DAC may convert the duty error value into another analogsignal with a corresponding voltage level and output the convertedanother analog signal as the reference voltage by feedback.

According to an example embodiment, the analog level meter may outputthe reference voltage as a measured value of the analog signal if theduty error value is a desired or predetermined value.

According to an example embodiment, the analog level meter may outputthe reference voltage as a measured value of the analog signal when theduty error value is 0.

According to an example embodiment, when the voltage level of the analogsignal is higher than the reference voltage, the up-down signal may bepositive, and when the voltage signal of the analog signal is lower thanthe reference voltage, the up-down signal may be negative.

According to an example embodiment, when the up-down signal is positive,the duty counter may increase the duty value by one, and when theup-down signal is negative, the duty counter may decrease the duty valueby one.

According to an example embodiment, the target duty value may be set tocorrespond to a target voltage of the analog signal to be measured.

According to an example embodiment, the target voltage may be a peakvoltage or a bottom voltage of the analog signal.

According to an example embodiment, the duty counter may count insynchronization with a desired or predetermined clock.

According to an example embodiment, the analog level detector mayinclude a subtracter, a low pass filter, and/or a residual accumulationintegrator.

According to an example embodiment, the subtracter may output the dutyerror value obtained by subtracting the target duty value from the dutyvalue of the up-down signal. The low pass filter may filter the dutyerror value. The residual accumulation integrator may output and holdthe filtered duty error value. The low pass filter may set differentweights for gains of the low pass filter by comparing the magnitude ofthe input of the low pass filter with the magnitude of the output of thelow pass filter.

According to an example embodiment, the low pass filter may removeripples of the duty error value.

According to an example embodiment, the analog level meter may furtherinclude a latch unit latching the duty value of the up-down signal ateach period in response to an update signal and/or an update signalgenerator generating the update signal at the each period.

According to an example embodiment, the analog level meter may furtherinclude a reset unit generating a reset signal for resetting the dutycounter at the each period. The reset unit may generate the reset signalby delaying the update signal.

According to an example embodiment a method of measuring a voltage levelof an analog signal may include comparing the voltage level of theanalog signal with a reference voltage, generating the comparison resultas an up-down signal, counting a duty value of the up-down signal,subtracting a target duty value from the duty value of the up-downsignal, converting the result of subtracting the target duty value fromthe duty value of the up-down signal into another analog signal with acorresponding voltage level and outputting the converted analog signalas the reference voltage by feedback, and/or outputting the result ofconverting the result of subtracting the target duty value from the dutyvalue of the up-down signal into the another analog signal with thecorresponding voltage level as a measured value of the analog signal ifthe result of subtracting the target duty value from the duty value ofthe up-down signal is a desired or predetermined value.

According to an example embodiment a method of measuring a voltage levelof an analog signal may include comparing the voltage level of theanalog signal with a reference voltage, generating the comparison resultas an up-down signal, counting a duty value of the up-down signal,subtracting a target duty value from the duty value of the up-downsignal, converting the result of subtracting the target duty value fromthe duty value of the up-down signal into another analog signal with acorresponding voltage level and outputting the converted analog signalas the reference voltage by feedback, and/or outputting the referencevoltage as a measured value of the analog signal if the result ofsubtracting the target duty value from the duty value of the up-downsignal is a desired or predetermined value.

According to an example embodiment, when the voltage level of the analogsignal is higher than the reference voltage, the up-down signal may bepositive, and when the voltage level of the analog signal is lower thanthe reference voltage, the up-down signal may be negative.

According to an example embodiment, in counting a duty value of theup-down signal, when the up-down signal is positive, the duty value ofthe up-down signal may be increased by one. In the counting a duty valueof the up-down signal, when the up-down signal is negative, the dutyvalue of the up-down signal may decreased by one.

According to an example embodiment, counting a duty value of the up-downsignal may be synchronized with a desired or predetermined clock.

According to an example embodiment, the target duty value may be set tocorrespond to a target voltage of the analog signal.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects and advantages will become more apparentand more readily appreciated from the following detailed description ofexample embodiments taken in conjunction with the accompanying drawingsof which:

FIG. 1 is an example diagram showing a conventional analog level meterwith an analog to digital converter;

FIGS. 2A and 2B are example circuit diagrams showing a conventionalpeak/bottom detector;

FIG. 3 is a schematic plan view showing an analog level meter using aduty ratio according to an example embodiment;

FIG. 4 is an example diagram showing an analog level detector shown inFIG. 3 according to an example embodiment; and

FIG. 5 is an example flow chart showing a method of measuring an analogsignal level using a duty ratio according to an example embodiment.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Example embodiments will now be described more fully hereinafter withreference to the accompanying drawings. Embodiments may, however, be inmany different forms and should not be construed as being limited to theexample embodiments set forth herein. Rather, these example embodimentsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope to those skilled in the art. In thedrawings, the thicknesses of layers and regions may be exaggerated forclarity.

It will be understood that when a component is referred to as being“on,” “connected to” or “coupled to” another component, it can bedirectly on, connected to or coupled to the other component orintervening components may be present. In contrast, when a component isreferred to as being “directly on,” “directly connected to” or “directlycoupled to” another component, there are no intervening componentspresent. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third,etc. may be used herein to describe various elements, components,regions, layers and/or sections, these elements, components, regions,layers and/or sections should not be limited by these terms. These termsare only used to distinguish one element, component, region, layer orsection from another element, component, region, layer or section. Thus,a first element, component, region, layer or section discussed belowcould be termed a second element, component, region, layer or sectionwithout departing from the teachings of the example embodiments.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one component or feature's relationship to another component(s)or feature(s) as illustrated in the drawings. It will be understood thatthe spatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. As usedherein, the singular forms “a,” “an” and “the” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements, and/orcomponents.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which example embodiments belong. Itwill be further understood that terms, such as those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Reference will now be made to example embodiments, which are illustratedin the accompanying drawings, wherein like reference numerals refer tothe like components throughout.

FIG. 3 is a schematic plan view showing an analog level meter using aduty ratio according to an example embodiment.

Referring to FIG. 3, the analog level meter 100 using a duty ratioaccording to an example embodiment may include a comparator 110, a dutycounter 120, an analog level detector 130 and/or a digital to analogconverter (DAC) 140.

The comparator 110 may compare a voltage level of the analog signalXANAL to be measured with a reference voltage VREF and generate anup-down signal XUD. The analog signal XANAL may be input into the anodeterminal of the comparator 110 and/or the reference voltage VREF may beinput into the cathode terminal of the comparator 110.

Accordingly, when the voltage level of the analog signal XANAL is higherthan the reference voltage, the up-down signal XUD may be positive, andwhen the voltage level of the analog signal XANAL is lower than thereference voltage VREF, the up-down signal XUD may be negative.

The duty counter 120 may count a duty value VDUTY of the up-down signalXUD. When the up-down signal XUD is positive, the duty counter 120 mayincrease the duty value VDUTY by one in response to the up-down signalXUD. Alternatively, when the up-down signal XUD is negative, the dutycounter 120 may decrease the duty value VDUTY by one.

The duty counter 120 may perform the counting in synchronization with adesired or predetermined clock CLK. The duty counter 120 may output theduty value VDUTY of the up-down signal XUD counted for a desired orpredetermined period.

Referring to FIG. 3, the analog level meter 100 may further include alatch unit 150 latching the duty value VDUTY of the up-down signal XUDat each period in response to an update signal XUDTE.

The update signal XUDTE may be generated by an update signal generator160. The update signal XUDTE may be a clock signal to be activated ateach period.

The update signal XUDTE may be applied to the duty counter 120 as areset signal XRSET through conversion. A reset unit 170 may generate thereset signal XRSET by delaying the update signal XUDTE. The duty counter120 may reset the duty value VDUTY at each period in response to thereset signal XRSET. For example, the reset unit may generate a resetsignal for resetting the duty counter after latching.

The duty value VDUTY of the up-down signal XUD may be transmitted to theanalog level detector 130 at each period. The analog level detector 130may output a duty error value Du_Err obtained by subtracting a targetduty value TDUTY from the duty value VDUTY of the up-down signal XUD.

FIG. 4 is an example diagram showing an analog level detector shown inFIG. 3 according to an example embodiment.

Referring to FIGS. 3 and 4, the analog level detector 130 may include asubtracter 131, a low pass filter 132 and/or a residual accumulationintegrator 133.

The subtracter 131 may output the duty error value (Du_Err) obtained bysubtracting a target duty value TDUTY from the duty value VDUTY of theup-down signal XUD. The target duty value TDUTY may be set to correspondto a target voltage of the analog signal XANAL to be measured.

The target voltage may be the voltage of the analog signal XANAL to bemeasured. Accordingly, the target voltage may be a peak/bottom voltageof the analog signal. However, the target voltage may be set to 90% or99% of the peak/bottom voltage of the analog signal XANAL.

The low pass filter 132 may filter the duty error value Du_Err. Forexample, the low pass filter 132 may remove ripples of the duty errorvalue Du_Err. The residual accumulation integrator 133 may output andhold the filtered duty error value Du_Err.

The low pass filter 132 may include a comparison unit. The comparisonunit may compare the magnitude of the input of the low pass filter 132with the magnitude of the output of the low pass filter 132. Thecomparison unit may set different weights for gains (C0, C1) of the lowpass filter according to the comparison result of the magnitude of theinput and the output of the low pass filter 132.

For example, at first, the duty error value Du_Err may be +1 as for theinput IN of the low pass filter 132, and then the duty error valueDu_Err may be −1 as for the input IN of the low pass filter 132.

In the low pass filter 132 according to an example embodiment, themagnitude of the input IN may be less than the magnitude of the outputOUT, so the low pass filter 132 may set a weight 1 (C0_ma) for CO andset a weight 0.1 (C1_s1) for C1. The output OUT may be as follows:((+1)×1)+((−1)×0.1)=0.9. Accordingly, the duty error value Du_Err may bedetected as 0.9.

Alternatively, at first, the duty error value Du_Err may be −1 as forthe input IN of the low pass filter 132, and then the duty error valueDu_Err may be +1 as for the input IN of the low pass filter 132.

In the low pass filter 132 according to an example embodiment, themagnitude of the input IN may be greater than the magnitude of theoutput OUT, so the low pass filter 132 may set a weight 0.1 (CO_s1) forC0 and set a weight 1 (C1_ma) for C1. The output OUT may be as follows:(−1)×1)+((+1)×0.1)=(−0.9). Accordingly, the duty error value Du_Err maybe detected as −0.9.

For example, the duty error value Du_Err may be varied with the periods,and/or the peak/bottom value of the ripples due to the variation of theduty error value Du_Err may be detected accurately, so an accurate dutyerror value Du_Err may be estimated.

Referring again to FIG. 3, the DAC 140 may convert the duty error valueDu_Err into an analog signal with a corresponding voltage level and mayoutput the converted analog signal as the reference voltage VREF byfeedback. When the duty error value Du_Err is a desired or predeterminedvalue of, for example, 0, the analog level meter 100 may output thereference voltage VREF as the detected value (for example, the targetvoltage) of the analog signal XANAL.

The analog level meter using a duty ratio according to an exampleembodiment may solve many problems due to analog signals without usingan ADC. For example, it may be possible to resolve problems found incontrolling offset or gain of the analog signal and/or inaccurate leveldetection.

The analog signal detection may be performed digitally, so a user maymore easily deal with the detection of the analog signal level bysetting the clock period and/or the target voltage.

FIG. 5 is an example flow chart showing a method of measuring an analogsignal level using a duty ratio according to an example embodiment.

Referring to FIG. 5, a method 500 of measuring an analog signal levelusing a duty ratio according to an example embodiment may be a method ofmeasuring a voltage level of the analog signal. The method may includecomparing the voltage level of the analog signal with a referencevoltage (S510), generating a comparison result as a up-down signal(S520), counting a duty value of the up-down signal (S530), subtractinga target duty value from the duty value of the up-down signal (S540),converting the result of subtracting a target duty value from the dutyvalue of the up-down signal into another analog signal with thecorresponding voltage level and outputting the converted analog signalas the reference voltage by feedback (S550), and/or outputting theresult of converting the result of subtracting a target duty value fromthe duty value of the up-down signal into the another analog signal withthe corresponding voltage level as a measured value of the analogsignal, if the result of subtracting the target duty value from the dutyvalue of the up-down signal is a desired or predetermined value (S560)(For example, outputting the reference voltage as a measured value ofthe analog signal, if the result of subtracting the target duty valuefrom the duty value of the up-down signal is a desired or predeterminedvalue).

When the analog voltage level is higher than the reference voltage, theup-down signal may be positive, and when the analog voltage level islower than the reference voltage, the up-down signal may be negative.

In counting the duty value of the up-down signal (S530), when theup-down signal is positive, the duty value of the up-down signal may beincreased by one. Alternatively, in counting the duty value of theup-down signal (S530), when the up-down signal is negative, the dutyvalue of the up-down signal may be decreased by one.

Counting the duty value of the up-down signal (S530) may be performed ateach desired or predetermined clock. The target duty value may be set tocorrespond to the target voltage of the analog signal.

A method of measuring an analog signal level using a duty ratioaccording to an example embodiment may exist within the sprit or scopeof the aforementioned analog level meter. Accordingly, a method ofmeasuring an analog signal level according to an example embodiment willbe understood from the foregoing description, so a detailed descriptionabout the method of the measuring an analog signal level according to anexample embodiment will be omitted.

As described above, the voltage level of the analog signal may bemeasured by the analog level meter of example embodiments without anADC. A method of measuring an analog signal level using a duty ratioaccording to an example embodiment without an ADC may be used.Accordingly, sizes of the apparatuses and/or cost may be reduced.

Noise and/or offset voltage may be minimized through the digitalprocess. Because the user has only to set the target duty valuedifferently in order to change the voltage value to be measured, theuser may more easily change the voltage value to be measured and/ormeasure the accurate voltage value.

Although example embodiments have been shown and described in thisspecification and figures, it would be appreciated by those skilled inthe art that changes may be made to the illustrated and/or describedexample embodiments without departing from their principles and spirit,the scope of which is defined by the claims and their equivalents.

1. An analog level meter comprising: a comparator comparing a voltagelevel of an analog signal with a reference voltage and generating anup-down signal; a duty counter counting a duty value of the up-downsignal; an analog level detector outputting a duty error value obtainedby subtracting a target duty value from the duty value of the up-downsignal; and a digital to analog converter DAC converting the duty errorvalue into another analog signal with a corresponding voltage level andoutputting the converted another analog signal as the reference voltageby feedback, wherein the analog level meter outputs the referencevoltage as a measured value of the analog signal when the duty errorvalue is a value.
 2. The analog level meter of claim 1, wherein theanalog level meter outputs the reference voltage as a measured value ofthe analog signal when the duty error value is
 0. 3. The analog levelmeter of claim 1, wherein the up-down signal is positive when thevoltage level of the analog signal is higher than the reference voltage,and wherein the up-down signal is negative when the voltage level of theanalog signal is lower than the reference voltage.
 4. The analog levelmeter of claim 3, wherein the duty counter increases the duty value byone when the up-down signal is positive, and wherein the duty counterdecreases the duty value by one when the up-down signal is negative. 5.The analog level meter of claim 1, wherein the target duty value is setto correspond to a target voltage of the analog signal.
 6. The analoglevel meter of claim 5, wherein the target voltage is a peak voltage ora bottom voltage of the analog signal.
 7. The analog level meter ofclaim 1, wherein the duty counter counts in synchronization with aclock.
 8. The analog level meter of claim 1, wherein the analog leveldetector includes a subtracter outputting the duty error value obtainedby subtracting the target duty value from the duty value of the up-downsignal; a low pass filter filtering the duty error value; and a residualaccumulation integrator outputting and holding the filtered duty errorvalue.
 9. The analog level meter of claim 8, wherein the low pass filtersets different weights for gains of the low pass filter by comparing themagnitude of the input of the low pass filter with the magnitude of theoutput of the low pass filter.
 10. The analog level meter of claim 1,further comprising: a latch unit latching the duty value of the up-downsignal at each period in response to an update signal.
 11. The analoglevel meter of claim 10, further comprising: an update signal generatorgenerating the update signal at the each period.
 12. The analog levelmeter of claim 11, further comprising: a reset unit generating a resetsignal for resetting the duty counter at the each period.
 13. The analoglevel meter of claim 12, wherein the reset unit generates the resetsignal by delaying the update signal.
 14. A method of measuring avoltage level of an analog signal, the method comprising: comparing thevoltage level of the analog signal with a reference voltage; generatingthe comparison result as an up-down signal; counting a duty value of theup-down signal; subtracting a target duty value from the duty value ofthe up-down signal; converting the result of subtracting the target dutyvalue from the duty value of the up-down signal into another analogsignal with a corresponding voltage level and outputting the convertedanother analog signal as the reference voltage by feedback; andoutputting the reference voltage as a measured value of the analogsignal when the result of subtracting the target duty value from theduty value of the up-down signal is a value.
 15. The method of claim 14,wherein the up-down signal is positive when the voltage level of theanalog signal is higher than the reference voltage, and wherein theup-down signal is negative when the voltage level of the analog signalis lower than the reference voltage.
 16. The method of claim 15, whereincounting a duty value of the up-down signal includes increasing the dutyvalue of the up-down signal by one when the up-down signal is positive,and decreasing the duty value of the up-down signal by one when theup-down signal is negative.
 17. The method of claim 14, wherein countinga duty value of the up-down signal is synchronized with a clock.
 18. Themethod of claim 14, wherein the target duty value is set to correspondto a target voltage of the analog signal.